I believe this question is trying to get you to realize the difference between acquired traits(one you get through doing something during life) and heritable traits(ones from Mom/Dad). For example, I really wish I was 6 foot 4... but the height trait comes genetically from your parents since it is coded in my DNA how tall I will be, therefore this trait must be passed down genetically and somewhere down the evolutionary tree the humans in the region which my family comes from was better off being short. An example that comes from acquired traits could be muscularity... my parents are both not very muscular but throughout my lifetime I enjoy working out and have become much more muscular, no matter how much your parents or grandparents lift weights YOU won't change so that change must be acquired through aging during your lifetime. Now the amount of muscle your body can put on is a heritable thing but that is beside the point. Hope this helps :)
The answer is D, photosynthesis and respiration.
—Evidence—
Oxygen is a byproduct of photosynthesis and, correspondingly, carbon dioxide the byproduct of respiration.
Oxygen gives our cells the ability to break down food in order to get the energy we need to survive. Although other animals may use different organs to breathe with, they all get oxygen into their bodies through respiration.
Answer:
Parathyroid hormone increases the level of calcium while calcitonin hormone decreases the level of calcium in the blood.
Explanation:
Parathyroid hormone is a type of harmone which is responsible for balancing calcium in our body. When the calcium level lowers in our body, parathyroid hormone is secreted and calcium is absorbed from the bones and fullfilled the requirement of the body. If the tumor secreted calcitonin hormone instead of parathyroid hormone, the calcium level in the blood is lowered because it acts to the opposite of parathyroid hormone.
They are all the examples of organ system.
